The present invention relates to valveless chemical cartridge respirators for filtration of vinyl chloride monomer (VCM) and having an end of service life indicator as an integral part thereof. So far as is known, all commercially available chemical cartridge respirators are equipped with inhalation and exhalation valves. Inhalation valves prevent exhaled air from entering the cartridge and contaminating the filter media with excess humidity. Exhalation valves permit easier exhalation since the resistance to flow of air therethrough is very low.
The prior art, including various governmental agencies, has treated as inviolable fact that respirators for toxic vapors and gases must be equipped with inhalation and exhalation valves to be effective. Thus, reference to Subpart L of Part 11 of Subchapter B of Chapter 1, Title 30, Code of Federal Regulations, Federal Register, Vol. 37, No. 59, March 25, 1972, and Subpart N, Federal Register, Vol. 39, No. 251, Dec. 30, 1974, (hereafter to be referred to as 30 CFR Part 11, Subpart and Section) will comfirm the fact that approval of chemical cartridge respirators is predicated on structures containing inhalation and exhalation valves. The Australian Standards CZ11 and Z18-1968 for "Respiratory Protective Devices" and British Standard BS 2091: 1969 for "Respirators for Protection Against Harmful Dusts and Gases" are similarly premised.